COVER STORY DESIGNING THERMALLY COMFORTABLE, LOW-ENERGY HOMES “C omfort is behaviour… occupants create tempera- ture… not always, but at least at home we do…” 1 How to design homes that meet the dwellers’ thermal demands for comfort while using the least amount of energy? What strategies do I normally use to remain thermally comfortable at home? Several studies confirm that dwellers feel more comfortable at home than in the office. This is explained in part because at home thermostats are more readily available and changes to thermostat room temperatures are felt faster. A meta-analysis from field data from various countries concludes2 : “on the one hand a mechanical system allows dwellers to exercise a considerable degree of control over indoor temperatures, which results in temperature variabilities reflecting their particular thermal preferences; on the other hand, the temperatures found in naturally conditioned buildings are largely determined by the form and character of the building and the response of the dwellers to the environment.” Home characteristics influence our behaviours at home. A field study in Denmark suggests that the energy efficiency of homes affects the dwellers’ energy-consuming habits, with correlations moderated by the socio-demographic characteristics of the dwellers. Study correlations suggest that occupants dress lighter and keep higher temperatures in energy-efficient houses, leading to increased energy demand due to changed comfort expectations (i.e. a rebound effect). However, building characteristics were found to be less influential on the frequency of opening windows.3 Our personal background and whether we own or rent our home affect how we use it. A recent study in social housing in British Columbia4 revealed that occupants were not concerned about energy waste because they do not pay the utility bills. Therefore, they were often not careful about opening their windows in cold weather. A field study in Australian residences5 reveals that the role of occupants is significant in the household thermal energy consumption. The study authors explain that given the diverse activities within, and high levels of personal control over, the indoor environment compared to offices, occupants’ behaviour is one of the key uncertainties in predicting energy use in the residential sector. By Rodrigo Mora, P.Eng., PhD, Faculty, Building Science Graduate Program, BCIT Introduction to residential thermal comfort design SPRING/SUMMER 2019 17